Tomographic Imaging Systems
Creation of a Prototype of the Tomographic Imaging System Using Quasi-uniform Geometry for Application to Inertial Confinement Fusion
Tech Area / Field
- FUS-ICS/Inertial Confinement Systems/Fusion
8 Project completed
Senior Project Manager
Komarkov D A
FIAN Lebedev, Russia, Moscow
- State Enterprise Krasnaya Zvezda, Russia, Moscow
- W.J.Schafer Corporation, USA, CA, Livermore\nOsaka University / Institute of Laser Engineering, Japan, Osaka
Project summaryThe goal of the Project is to create the tomographing imaging system for precise and accurate characterization of inertial confinement fusion (ICF) micro- objects such as, for example, micro-shells and cryogenic targets.
Expected results are the following:
1. A high resolution algorithm for micro- object reconstruction. Results of the numerical experiments on testing the created algorithm.
2. The prototype of a tomograph which includes:
- tomographic test chamber (overall dimensions no more than 20x20x20 cm),
- device to deliver a target to the test chamber (overall dimensions no more than 40x40x100 cm),
- radiation source ( a gas laser of no more than 10 mW power and/or non-coherent light source),
- scanning system,
- radiation receiver (CCD-matrix not less than 1000x1000 pixels),
- adapter for entering micro-object scanning results in a computer (frame-grabber).
The tomograph prototype will supplement the Free-Standing Target System (the system has been created in the scope of the ISTC project #512) with a reliable diagnostic subsystem needed for the Fall-and-Strike Technique (FST, fuel layering technique developed at the LPI) to be well documented.
The technical approach has the bases in the development of the tomographic information processing methods allowing for building a reliable diagnostic system for determination of the cryogenic target parameters.
The choice of the technical approach follows from the fact that the conventional characterization methods (interferometric and holographic, schliren system and etc.) allow the estimation of only average values (integral characteristics) with a high precision because they work in one or several views (projections).
In the case of the cryogenic layer, the fuel uniformity, concentricity and sphericity are better than 2%; fuel layer surface finish is better than 1 m. Thus, the methods for determination of these characteristics of the target should provide for a three-dimension reconstruction of the interior target structure with a required precision. In turn, this calls for further development of new field of characterization based on tomographic information processing methods, that is mathematical treatment of the information (image projection data) obtained as a result of micro-object scanning.
The algorithm of spatial micro-object reconstruction is one of the most important constituents of tomography. It is being developed concurrently with the optimal scanning scheme selecting for a given radiation source.
Further optimization and adaptation of the algorithm and the scanning scheme to the micro-object specifics is the next important step of our activity. That is realized using a set of the integral characteristics (or image projection data) obtained for special test- objects. The Project assumes to develop two prototypes for this purpose: the first to deal with micro-shells at 300K and the second – with cryogenic targets inside the test chamber of the cryostat at 4.2 – 20K.
The main stages of micro-object preparation for tomography are the following:
- micro-shell production and selection;
- micro-shells filling with gas;
- cryogenic target fabrication by the FST method that provides fast cryogenic layer formation inside an unmounted shell during its movement along the layering channel under gravity (I.V.Aleksandrova et.al, Fusion Тechnology 38, No1, p.166, 2000).
The produced cryogenic targets are injected from the layering channel to the test chamber and then characterized. The elaboration of a special test chamber compatible with both the tomograph optical train and the scanning system is an important task of the Project.
Scope of activity.
· Micro-object modeling
· Algorithm creating
· Creation of the tomograph prototype, including
- the optical high spatial resolution train
- the tomographic test chamber
- the device for cryogenic target delivery into the tomographic test chamber
- the scanning system
- the models of the elements
· Micro-object characterization using the created prototype of the tomograph
The main tasks of the 1st year are the developments of special tools for creating, testing and optimization of the reconstruction algorithm and the scanning scheme. The tools are:
- a numerical ray trace model which simulates the backlit images of transparent spherical ICF targets in three dimensions;
- a preliminary model of the prototype capable of operating with micro-shells at room temperature.
The main tasks of the 2nd year are (a) development of the reconstruction algorithm and scanning scheme, and (b) construction of the basical elements of the tomograph prototype.
The main tasks of the 3rd year are the algorithm and the tomograph prototype testing and improvement.
Main results of the first year:
· Creation of the numerical model of the light propagation through the multi layer shell supplied with the interface program compatible with Windows-98.
· Creation of the preliminary model of the tomograph prototype capable of operating with micro-shells at room temperature.
· Development of the method to form the solid cryogenic layer of the hydrogen isotopes transparent for the visible light over the whole range of its solid phase.
Conference presentations and papers published over the period of the first year
1. I.V.Aleksandrova, S.V.Bazdenkov, V.I.Chtcherbakov, Rapid fuel-layering inside moving free-standing ICF targets: physical model and simulation code development, Report at the 26th European conference on Laser Interaction with Matter (ECLIM 2000,12-16 June 2000, Prague, Czech Republic); Proc. of SPIE 4424, p.197 (2001)
2. E.R.Koresheva, I.V.Aleksandrova, I.E.Osipov, G.D.Baranov, I.D.Timofeev, S.V.Bazdenkov, A.A.Belolipetskiy, V.I.Chtcherbakov, E.L.Koshelev, V.I.Listratov, L.A.Rivkis, V.G.Soloviev, T.P.Timasheva, S.M.Tolokonnikov, G.S.Usachev, V.P.Veselov, A free-standing target system for application to high-power laser experiments, Report at the IAEA Technical Committee Meeting on Physics and Technology of Inertial Fusion Energy (June 5 – 11, 2000, Madrid, Spain)
3. E.R.Koresheva, I.E.Osipov, T.P.Timasheva, L S.Yaguzinskiy, The issue of homogeneous solid H2-layers formation inside free-standing microshells, Proc. 2nd International Conference on the Inertial Fusion Science and Applications (IFSA-2001, September 9-14, 2001, Kyoto, Japan)
4. I.V.Aleksandrova, G.D.Baranov, S.V.Bazdenkov, A.A.Belolipetskiy, V.I.Golov, V.I.Chtcherbakov, E.R.Koresheva, E.L.Koshelev, V.I.Listratov, A.M.Lotkov, E.V.Makeeva, A.I.Nikitenko, I.E.Osipov, E.A.Pisarnitskaya, T.P.Timasheva, I.D.Timofeev, S.M.Tolokonnikov, G.S.Usachev, L.S.Yaguzinskiy, Creation of a tomograph prototype for cryogenic target characterization, Report, ibid.
5. E.R.Koresheva, O.N.Krokhin, I.V.Aleksandrova, I.E.Osipov, Status of the Lebedev Physical Institute in ICF- and IFE- cryogenics, Report, ibid.
6. I.E.Osipov, I.V. Aleksandrova, G.D.Baranov, S.V. Bazdenkov, V.I.Chtcherbakov, E.R.Koresheva, E.L.Koshelev, V.I.Listratov, A.M.Lotkov, E.V.Makeeva, A.I.Nikitenko, T.P.Timasheva, I.D.Timofeev, S.M.Tolokonnikov, G.S.Usachev, L.S.Yaguzinskiy, Demonstrated performance of free-standing target system, Report, ibid.
7. E.R.Koresheva, O.N.Krokhin, I.E.Osipov, T.P.Timasheva, L S.Yaguzinskiy, Russian Patent, claim No 2001121680 of August 9, 2001
8. I.V.Aleksandrova, A.A.Belolipetskiy, V.I.Golov, V.I.Chtcherbakov, E.V.Makeeva, E.R.Koresheva, l.E.Osipov. Progress in the development of tomographic information processing methods for applications to ICF target characterization. Fusion Technology 38 N2 p.190, September 2000
9. E.R.Koresheva, I.E.Osipov, T.P.Timasheva, L S.Yaguzinskiy. A new method of fabrication of the transparent solid hydrogen layer inside a microshell: the application to inertial confinement fusion. J.Appl.Physics D (in press)
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